1. Field of the Invention
The present invention relates to an image forming apparatus such as a photocopier, a printer, a facsimile, and a multifunction machine. More particularly, the present invention relates to a cleaning device and a cleaning method using the cleaning device for image forming apparatuses.
2. Description of the Related Art
Generally, an image forming apparatus is classified into a monochrome image forming apparatus and a color image forming apparatus. The monochrome image forming apparatus generates an image in black-and-white by using a monochromic developer. Alternatively, the color image forming apparatus generates an image in color by using color developers typically based on the following colors: magenta, cyan, yellow and black.
As is also well known, an electrophotographic image forming apparatus generates an image by sequential steps. In the case of the monochrome image forming apparatus, first, a charging unit charges a photosensitive medium with a predetermined electric potential. Then, a scanning unit scans a laser beam to generate an electrostatic latent image. The electrostatic latent image is developed into a monochrome developer and then transferred into a visible image on a printing paper. In the case of the color image forming apparatus, the electrostatic latent image is developed into each color developer on the photosensitive medium. Afterwards, a superimposed image is transferred to a transfer belt, and a full color image is developed on a printing paper. Additionally, a cleaning device may be provided for removing waste developers remaining after being transferred by the transfer belt or the photosensitive medium.
FIG. 1 is a diagram schematically showing a conventional cleaning device of a wet-type color image forming apparatus using a liquid developer.
As shown, the cleaning device 50 comprises a transfer belt 40; a cleaning blade 52 is disposed on one side of the transfer belt 40 and makes contact with the transfer belt 40; and a support bracket 54 supports the cleaning blade 52. Usually, the cleaning blade 52 is made of a ductile material having elasticity, and the support bracket 54 is fixed to the cleaning blade 52 and to a body (not shown) of the image forming apparatus or another support bracket (not shown).
Referring to FIG. 1, cleaning steps and steps of generating an image in a conventional cleaning device will be described in detail. A scanning unit 20 generates an electrostatic latent image on photosensitive drums 10 for each individual color, and color developers supplied from each of several color developing units 30 are transferred to the photosensitive drums 10. The color developers are superimposed on the transfer belt 40. The superimposed color developers are then transferred into a visible image on printing paper P passing through a drive roller 41 and a transfer roller 60. Waste developer 70 remaining after the transfer stays on the transfer belt and moves along with the transfer belt 40.
As shown in FIG. 1, the remaining waste developer 70 is removed by the cleaning blade 52 disposed in contact with the transfer belt 40, so that the remaining waste developer 70 flows by gravity along one surface of the cleaning blade 52.
However, the conventional cleaning device has a problem in that the remaining waste developer 70 is deposited on the cleaning blade 52. In the case of a high-speed printing process, or in the case of a high quantity of materials being printed, waste developer deposition occurs due to an increased amount of the remaining waste developer 70. Particularly, in instances using a liquid type developer, because of viscousness of the developers, greater quantities of developers are deposited on one surface of the cleaning blade 52.
As the remaining waste developer 70 is deposited on the cleaning blade 52, pressure is created as the cleaning blade 52 presses the transfer belt 40, e.g., a pressure exerted in a predetermined direction denoted by arrow ‘Y’ in FIG. 1, increases, and this increased pressure may result in damage to a surface of the transfer belt 40. Also, cleaning performance may decrease, which may further increase the likelihood of generating an incomplete and unstable image.
Accordingly, there is a continual need for image apparatuses with improved cleaning devices and cleaning methods for removing waste developers.